This grant requests funds for the purchase of a BIAcore 3000 surface plasmon resonance instrument for the analysis of biomolecular interactions in a variety of systems. The Biology and Biochemistry Departments of Brandeis do not currently possess any instruments with the capabilities of a BIAcore 3000 for the analysis of protein-protein, protein-membrane, protein-small molecule and protein-DNA interactions. The acquisition of a BIAcore instrument would significantly enhance the research capabilities of the life science group at Brandeis. The instrument would be housed in the Core Biomolecules Synthesis and Analysis Facility. This facility is staffed and instrument management mechanisms (financial, maintenance) are already in place and will be supplemented to accommodate the BIAcore. The BIAcore 3000 would be accessible to all NIH-supported investigators at Brandeis University as well as others on a time-available basis. The six investigators in the user group are interested in both traditional uses of the instrument (kinetics and equilibria of protein-protein interactions) and in development of new techniques. Projects include: regulation of CaM trapping by autophosphorylation of CaMKII isoforms; characterization of assembly of synaptic protein complexes; characterization of ligand/inhibitor binding and protein domain interactions of IMPPDH; regulation of exonuclease ssDNA binding by auxiliary subunits; characterization of splicing factor protein-protein interactions; measurement of Ab:Ag affinities during B cell differentiation; identification of ligands for orphan nuclear hormone receptors. Institutional commitment for acquisition and maintenance of a BIAcore 3000 is high. The salary of the Principal Operator, as well as space in the Facility, and funds for maintenance of the instrument are guaranteed into the foreseeable future.